Pyrene Excimer Method for Quantifying Polymer Intermolecular Interactions
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Solution Overview
Problem
Current methods for quantifying intermolecular associations between macromolecules in solutions, such as fluorescence resonance energy transfer (FRET), often fail to provide a quantitative measure of the molar fraction of macromolecules involved in intermolecular associations due to the complex relationship between FRET efficiency and the distribution of donor-acceptor distances.
Innovation Solution
A method involving fluorescent dye-labeled macromolecules, where the fluorescence intensities of excimers and monomers in solutions at different concentrations are measured to determine the level of intermolecular interaction using specific ratios, allowing for the calculation of the fraction of intermolecular interaction relative to total molecular interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FRET is used to probe intermolecular associations, then evidence of intermacromolecular interactions can be obtained, but a quantitative measure of the molar fraction of macromolecules involved in intermolecular associations is rarely provided
Solution Approach 1:
The patent introduces an intramolecular excimer formation process as an intermediary mechanism that serves as a reference system. By comparing intermolecular excimer formation (which indicates polymer-polymer interactions) against intramolecular excimer formation (which occurs within single polymer chains), the method provides a quantitative measure of intermolecular associations without requiring complex FRET efficiency calculations. The intramolecular process acts as a built-in control that simplifies the quantification of intermolecular interactions.
Solution Approach 2:
The patent changes the measurement parameter from FRET efficiency (which has a complex relationship with distance distribution) to excimer fluorescence intensity ratios. By monitoring the ratio of excimer to monomer fluorescence intensities at different concentrations, the method transforms a complex structural parameter into a simpler optical parameter that directly correlates with the fraction of intermolecular interactions, enabling straightforward quantitative analysis.
2Loss of information
If FRET efficiency is used to infer interaction strength, then qualitative information about intermacromolecular interactions can be obtained, but the actual level of association (molar fraction) cannot be easily determined
Solution Approach 1:
The patent uses intramolecular excimer formation as an intermediary reference process that occurs within individual polymer chains. By establishing this intramolecular baseline and comparing it against intermolecular excimer formation, the method recovers the lost quantitative information about molar fractions. The intermediary intramolecular process provides a reference framework that enables conversion of qualitative fluorescence observations into quantitative association measurements.
Solution Approach 2:
The patent creates a copied reference system where intramolecular excimer formation serves as a model for what excimer formation looks like in the absence of intermolecular interactions. By having this copied intramolecular reference, the method can subtract or compare against it to isolate and quantify the intermolecular component, thereby recovering the molar fraction information that is otherwise lost in conventional FRET measurements.
3Productivity
If conventional fluorescence methods are used to study polymer interactions, then information about molecular associations can be obtained, but rapid and straightforward quantification of intermolecular interaction levels is not achieved
Solution Approach 1:
The patent merges the reference measurement and sample measurement into a single experimental system by using the same polymer molecules that exhibit both intramolecular and intermolecular excimer formation. By measuring the excimer-to-monomer intensity ratio in solutions of known concentration and comparing against a dilute reference, the method combines multiple measurement functions into one straightforward procedure, achieving rapid quantification without complex multi-step protocols.
Solution Approach 2:
The patent simplifies the measurement approach by changing from measuring absolute fluorescence intensities or FRET efficiencies to measuring excimer-to-monomer intensity ratios. This parameter transformation converts a complex measurement requiring detailed distance distribution analysis into a simple ratio measurement that can be quickly calculated and compared, dramatically increasing productivity while reducing computational complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a rapid and straightforward way to quantify intermolecular interactions, enabling the identification of suitable viscosity index improvers for lubricant compositions by determining the fraction of intermolecular interaction, which affects viscosity changes at various temperatures.
Implementation Method 1
measuring fluorescence intensities of excimers (IE) and fluorescence intensities of monomers (IM) of the first and second solutions
Implementation Method 2
The present disclosure is based on the unexpected development of a rapid and straightforward method to determine the intermolecular interaction of macromolecules (e.g. a polymer) by using fluorescent dye (e.g. pyrene) labeled macromolecules
Data Source
AI summary
The present invention relates to methods for determining the level of intermolecular interaction of a polymer based on the fraction of intermolecular interaction (finter) relative to the inter, total molecular interaction, which includes both intermolecular and intramolecular interactions. Further provided herein is a method of identifying a suitable viscosity index improver based on the value of finter. The identified suitable viscosity index improver can be used in a lubricating oil composition for, e.g., a power transmission system.